Preliminary Troubleshooting; Introduction; Module Or Troubleshooter Faulty; Module Or Interface Pod Faulty - Fluke 9000A-006 Service Manual

PRELIMINARY TROUBLESHOOTING

Introduction

The following paragraphs provide information to aid in the troubleshooting of the
Signature Module. The troubleshooting information is provided in descriptive form
followed by tables of signatures for selected test nodes on the module. Since the Interface
Pod depends on the Signature Module for the passage of the MAINSTAT and PODSTAT
signals that are necessary for Pod/Troubleshooter handshaking and communication, it is
first necessary to verify that the Interface Pod is not faulty. Also, since the Signature
Module depends on normal operation of the Troubleshooter, it is necessary to verify that
the Troubleshooter is not defective.
Once you have determined that a fault exists within the Signature Module, you can begin
troubleshooting the module. Troubleshooting the signature module involves verifying
signatures at designated test nodes.

Module or Troubleshooter Faulty?

The first step in troubleshooting the Signature Module is to determine that the module is
defective, not the Troubleshooter. You can make a quick check of Signature Module
operation by performing the equipment verification procedure contained in Section 2 of
the Operation Manual. If the module fails the functional test, but the Troubleshooter
operates satisfactorily when it is used with the Interface Pod, then the Signature Module is
defective.

Module or Interface Pod Faulty?

Although the Signature Module does not depend upon the Interface Pod for its operation,
the opposite is true. The Interface Pod depends on the Signature Module for the passage of
handshaking signals (MAINSTAT and PODSTAT) and data between itself and the
Troubleshooter. Because the signature module is electrically inserted in the handshaking/
data path to the Interface Pod, there is a failure mode of the Signature Module that can
render a good Interface Pod non-operational.
The failure mode occurs when the control section in the signature module prevents proper
generation and gating of the MAINSTAT and PODSTAT signals to and from the Interface
Pod. The failure may also interrupt the passage of data. The easiest way to verify that a
particular Interface Pod is operational, and not just being interfered with by the Signature
Module, is to use the pod with a known-good Troubleshooter to perform the pod self-test
or some similar operation. If a successful pod self-test is possible with the known-good
Troubleshooter, then the problem lies in the Signature Module or possibly in the
Troubleshooter.
If the control section of the Signature Module is suspect (due to apparent failure of the
Interface Pod) and a second Troubleshooter is not available for pod verification, it is
possible to temporarily disconnect and bypass the Signature Module, then check operation
of the Interface Pod. If the Interface Pod operates normally with the Signature Module
disconnected, the control section of the module is defective. To bypass the Signature
Module, refer to Disconnecting the Signature Module.

Disconnecting the Signature Module

Disconnection of the Signature Module may be performed whenever it is necessary to
remove it from the Troubleshooter/Interface Pod data and handshaking signal path. To
disconnect the Signature Module, perform steps 1 through 3a of the Disassembly
9000A-006 Service
3-7.
3-8.
3-9.
3-10.
3-11.
3-3